linux.git/kernel/kexec_file.c, branch v5.10.258

kexec: derive purgatory entry from symbol

2026-03-04T12:20:21+00:00

[ Upstream commit 480e1d5c64bb14441f79f2eb9421d5e26f91ea3d ]

kexec_load_purgatory() derives image->start by locating e_entry inside an
SHF_EXECINSTR section.  If the purgatory object contains multiple
executable sections with overlapping sh_addr, the entrypoint check can
match more than once and trigger a WARN.

Derive the entry section from the purgatory_start symbol when present and
compute image->start from its final placement.  Keep the existing e_entry
fallback for purgatories that do not expose the symbol.

WARNING: kernel/kexec_file.c:1009 at kexec_load_purgatory+0x395/0x3c0, CPU#10: kexec/1784
Call Trace:
 
 bzImage64_load+0x133/0xa00
 __do_sys_kexec_file_load+0x2b3/0x5c0
 do_syscall_64+0x81/0x610
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

[me@linux.beauty: move helper to avoid forward declaration, per Baoquan]
  Link: https://lkml.kernel.org/r/20260128043511.316860-1-me@linux.beauty
Link: https://lkml.kernel.org/r/20260120124005.148381-1-me@linux.beauty
Fixes: 8652d44f466a ("kexec: support purgatories with .text.hot sections")
Signed-off-by: Li Chen 
Acked-by: Baoquan He 
Cc: Alexander Graf 
Cc: Eric Biggers 
Cc: Li Chen 
Cc: Philipp Rudo 
Cc: Ricardo Ribalda Delgado 
Cc: Ross Zwisler 
Cc: Sourabh Jain 
Cc: Steven Rostedt 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Sasha Levin

kexec: support purgatories with .text.hot sections

2023-06-21T13:45:37+00:00

commit 8652d44f466ad5772e7d1756e9457046189b0dfc upstream.

Patch series "kexec: Fix kexec_file_load for llvm16 with PGO", v7.

When upreving llvm I realised that kexec stopped working on my test
platform.

The reason seems to be that due to PGO there are multiple .text sections
on the purgatory, and kexec does not supports that.


This patch (of 4):

Clang16 links the purgatory text in two sections when PGO is in use:

  [ 1] .text             PROGBITS         0000000000000000  00000040
       00000000000011a1  0000000000000000  AX       0     0     16
  [ 2] .rela.text        RELA             0000000000000000  00003498
       0000000000000648  0000000000000018   I      24     1     8
  ...
  [17] .text.hot.        PROGBITS         0000000000000000  00003220
       000000000000020b  0000000000000000  AX       0     0     1
  [18] .rela.text.hot.   RELA             0000000000000000  00004428
       0000000000000078  0000000000000018   I      24    17     8

And both of them have their range [sh_addr ... sh_addr+sh_size] on the
area pointed by `e_entry`.

This causes that image->start is calculated twice, once for .text and
another time for .text.hot. The second calculation leaves image->start
in a random location.

Because of this, the system crashes immediately after:

kexec_core: Starting new kernel

Link: https://lkml.kernel.org/r/20230321-kexec_clang16-v7-0-b05c520b7296@chromium.org
Link: https://lkml.kernel.org/r/20230321-kexec_clang16-v7-1-b05c520b7296@chromium.org
Fixes: 930457057abe ("kernel/kexec_file.c: split up __kexec_load_puragory")
Signed-off-by: Ricardo Ribalda 
Reviewed-by: Ross Zwisler 
Reviewed-by: Steven Rostedt (Google) 
Reviewed-by: Philipp Rudo 
Cc: Albert Ou 
Cc: Baoquan He 
Cc: Borislav Petkov (AMD) 
Cc: Christophe Leroy 
Cc: Dave Hansen 
Cc: Dave Young 
Cc: Eric W. Biederman 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Michael Ellerman 
Cc: Nathan Chancellor 
Cc: Nicholas Piggin 
Cc: Nick Desaulniers 
Cc: Palmer Dabbelt 
Cc: Palmer Dabbelt 
Cc: Paul Walmsley 
Cc: Simon Horman 
Cc: Thomas Gleixner 
Cc: Tom Rix 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

panic, kexec: make __crash_kexec() NMI safe

2023-04-20T10:10:29+00:00

commit 05c6257433b7212f07a7e53479a8ab038fc1666a upstream.

Attempting to get a crash dump out of a debug PREEMPT_RT kernel via an NMI
panic() doesn't work.  The cause of that lies in the PREEMPT_RT definition
of mutex_trylock():

	if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES) && WARN_ON_ONCE(!in_task()))
		return 0;

This prevents an nmi_panic() from executing the main body of
__crash_kexec() which does the actual kexec into the kdump kernel.  The
warning and return are explained by:

  6ce47fd961fa ("rtmutex: Warn if trylock is called from hard/softirq context")
  [...]
  The reasons for this are:

      1) There is a potential deadlock in the slowpath

      2) Another cpu which blocks on the rtmutex will boost the task
	 which allegedly locked the rtmutex, but that cannot work
	 because the hard/softirq context borrows the task context.

Furthermore, grabbing the lock isn't NMI safe, so do away with kexec_mutex
and replace it with an atomic variable.  This is somewhat overzealous as
*some* callsites could keep using a mutex (e.g.  the sysfs-facing ones
like crash_shrink_memory()), but this has the benefit of involving a
single unified lock and preventing any future NMI-related surprises.

Tested by triggering NMI panics via:

  $ echo 1 > /proc/sys/kernel/panic_on_unrecovered_nmi
  $ echo 1 > /proc/sys/kernel/unknown_nmi_panic
  $ echo 1 > /proc/sys/kernel/panic

  $ ipmitool power diag

Link: https://lkml.kernel.org/r/20220630223258.4144112-3-vschneid@redhat.com
Fixes: 6ce47fd961fa ("rtmutex: Warn if trylock is called from hard/softirq context")
Signed-off-by: Valentin Schneider 
Cc: Arnd Bergmann 
Cc: Baoquan He 
Cc: "Eric W . Biederman" 
Cc: Juri Lelli 
Cc: Luis Claudio R. Goncalves 
Cc: Miaohe Lin 
Cc: Petr Mladek 
Cc: Sebastian Andrzej Siewior 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Wen Yang 
Signed-off-by: Greg Kroah-Hartman

ima: force signature verification when CONFIG_KEXEC_SIG is configured

2022-07-21T19:20:11+00:00

[ Upstream commit af16df54b89dee72df253abc5e7b5e8a6d16c11c ]

Currently, an unsigned kernel could be kexec'ed when IMA arch specific
policy is configured unless lockdown is enabled. Enforce kernel
signature verification check in the kexec_file_load syscall when IMA
arch specific policy is configured.

Fixes: 99d5cadfde2b ("kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE")
Reported-and-suggested-by: Mimi Zohar 
Signed-off-by: Coiby Xu 
Signed-off-by: Mimi Zohar 
Signed-off-by: Sasha Levin

kexec_file: drop weak attribute from arch_kexec_apply_relocations[_add]

2022-06-09T08:21:26+00:00

commit 3e35142ef99fe6b4fe5d834ad43ee13cca10a2dc upstream.

Since commit d1bcae833b32f1 ("ELF: Don't generate unused section
symbols") [1], binutils (v2.36+) started dropping section symbols that
it thought were unused.  This isn't an issue in general, but with
kexec_file.c, gcc is placing kexec_arch_apply_relocations[_add] into a
separate .text.unlikely section and the section symbol ".text.unlikely"
is being dropped. Due to this, recordmcount is unable to find a non-weak
symbol in .text.unlikely to generate a relocation record against.

Address this by dropping the weak attribute from these functions.
Instead, follow the existing pattern of having architectures #define the
name of the function they want to override in their headers.

[1] https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=d1bcae833b32f1

[akpm@linux-foundation.org: arch/s390/include/asm/kexec.h needs linux/module.h]
Link: https://lkml.kernel.org/r/20220519091237.676736-1-naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Michael Ellerman 
Signed-off-by: Naveen N. Rao 
Cc: "Eric W. Biederman" 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

kernel: kexec_file: fix error return code of kexec_calculate_store_digests()

2021-05-19T08:13:09+00:00

[ Upstream commit 31d82c2c787d5cf65fedd35ebbc0c1bd95c1a679 ]

When vzalloc() returns NULL to sha_regions, no error return code of
kexec_calculate_store_digests() is assigned.  To fix this bug, ret is
assigned with -ENOMEM in this case.

Link: https://lkml.kernel.org/r/20210309083904.24321-1-baijiaju1990@gmail.com
Fixes: a43cac0d9dc2 ("kexec: split kexec_file syscall code to kexec_file.c")
Signed-off-by: Jia-Ju Bai 
Reported-by: TOTE Robot 
Acked-by: Baoquan He 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

ima: Free IMA measurement buffer after kexec syscall

2021-03-04T10:37:50+00:00

[ Upstream commit f31e3386a4e92ba6eda7328cb508462956c94c64 ]

IMA allocates kernel virtual memory to carry forward the measurement
list, from the current kernel to the next kernel on kexec system call,
in ima_add_kexec_buffer() function.  This buffer is not freed before
completing the kexec system call resulting in memory leak.

Add ima_buffer field in "struct kimage" to store the virtual address
of the buffer allocated for the IMA measurement list.
Free the memory allocated for the IMA measurement list in
kimage_file_post_load_cleanup() function.

Signed-off-by: Lakshmi Ramasubramanian 
Suggested-by: Tyler Hicks 
Reviewed-by: Thiago Jung Bauermann 
Reviewed-by: Tyler Hicks 
Fixes: 7b8589cc29e7 ("ima: on soft reboot, save the measurement list")
Signed-off-by: Mimi Zohar 
Signed-off-by: Sasha Levin

kernel/resource: move and rename IORESOURCE_MEM_DRIVER_MANAGED

2020-10-16T18:11:18+00:00

IORESOURCE_MEM_DRIVER_MANAGED currently uses an unused PnP bit, which is
always set to 0 by hardware.  This is far from beautiful (and confusing),
and the bit only applies to SYSRAM.  So let's move it out of the
bus-specific (PnP) defined bits.

We'll add another SYSRAM specific bit soon.  If we ever need more bits for
other purposes, we can steal some from "desc", or reshuffle/regroup what
we have.

Signed-off-by: David Hildenbrand 
Signed-off-by: Andrew Morton 
Cc: Michal Hocko 
Cc: Dan Williams 
Cc: Jason Gunthorpe 
Cc: Kees Cook 
Cc: Ard Biesheuvel 
Cc: Pankaj Gupta 
Cc: Baoquan He 
Cc: Wei Yang 
Cc: Eric Biederman 
Cc: Thomas Gleixner 
Cc: Greg Kroah-Hartman 
Cc: Anton Blanchard 
Cc: Benjamin Herrenschmidt 
Cc: Boris Ostrovsky 
Cc: Christian Borntraeger 
Cc: Dave Jiang 
Cc: Haiyang Zhang 
Cc: Heiko Carstens 
Cc: Jason Wang 
Cc: Juergen Gross 
Cc: Julien Grall 
Cc: "K. Y. Srinivasan" 
Cc: Len Brown 
Cc: Leonardo Bras 
Cc: Libor Pechacek 
Cc: Michael Ellerman 
Cc: "Michael S. Tsirkin" 
Cc: Nathan Lynch 
Cc: "Oliver O'Halloran" 
Cc: Paul Mackerras 
Cc: Pingfan Liu 
Cc: "Rafael J. Wysocki" 
Cc: Roger Pau Monné 
Cc: Stefano Stabellini 
Cc: Stephen Hemminger 
Cc: Vasily Gorbik 
Cc: Vishal Verma 
Cc: Wei Liu 
Link: https://lkml.kernel.org/r/20200911103459.10306-3-david@redhat.com
Signed-off-by: Linus Torvalds

fs/kernel_file_read: Add "offset" arg for partial reads

2020-10-05T11:37:04+00:00

To perform partial reads, callers of kernel_read_file*() must have a
non-NULL file_size argument and a preallocated buffer. The new "offset"
argument can then be used to seek to specific locations in the file to
fill the buffer to, at most, "buf_size" per call.

Where possible, the LSM hooks can report whether a full file has been
read or not so that the contents can be reasoned about.

Signed-off-by: Kees Cook 
Link: https://lore.kernel.org/r/20201002173828.2099543-14-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman

fs/kernel_read_file: Add file_size output argument

2020-10-05T11:37:03+00:00

In preparation for adding partial read support, add an optional output
argument to kernel_read_file*() that reports the file size so callers
can reason more easily about their reading progress.

Signed-off-by: Kees Cook 
Reviewed-by: Mimi Zohar 
Reviewed-by: Luis Chamberlain 
Reviewed-by: James Morris 
Acked-by: Scott Branden 
Link: https://lore.kernel.org/r/20201002173828.2099543-8-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman